Michigan is in the minority of states that do not consider relative age. In most other states, if two people below the age of consent have sex, it is legal (or a less severe crime) as long as the partners are close to the same age.
Moreover, the Michigan age of consent law is absolute – it is illegal to have sex with anyone who is below the age of consent, no matter their relative age. If people have sex, and both of them are 15, both are committing a crime.
In Michigan, age of consent laws only specifically apply to heterosexual conduct. However, as a general rule, age of consent laws in the United States apply to homosexual conduct the same as heterosexual conduct, even if the statutes do not directly address this issue.
A valid defense to violation of age of consent law is marriage. Moreover, a mistake of age is not a defense.
If you may be in violation of the age of consent law, please contact a Michigan criminal defense lawyer for your best course of action.